/* 
 * [New BSD License (BSD 3-Clause License)]
 * Copyright (c) 2012, Max Bechtold
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *     - Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     - Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     - Neither the name of the Rel2Xml Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package maxbe.rel2xml.generator.dml.predicates;

/**
 * Interface that describes predicates
 * 
 * @author Max Bechtold
 */
public interface Predicate {

	public static enum Comparison {
		EQUAL("="),

		NOT_EQUAL("<>"),

		GREATER(">"),

		GREATER_OR_EQUAL(">="),

		LESS("<"),

		LESS_OR_EQUAL("<=");

		private final String operator;

		Comparison(String operator) {
			this.operator = operator;
		}

		public String getOperator() {
			return operator;
		}

		public static Comparison parseComparison(String operator) {
			for (Comparison comparison : values()) {
				if (comparison.operator.equals(operator)) {
					return comparison;
				}
			}
			return null;
		}
	}

	/**
	 * Returns an XQuery predicate applicable in a where-clause
	 */
	public String toXQuery();

	/**
	 * Returns an XQuery but omits alias references in form of variables. Used
	 * in bracketed predicates
	 */
	public String toXQuery(boolean omitAliases);

	/**
	 * Returns an SQL equivalent of this predicate
	 */
	public String toSql();
}
